A process for producing a corresponding unsaturated aldehyde and unsaturated carboxylic acid using propylene, isobutylene, or tertiary butanol as a raw material has been industrially widely implemented, but generation of a local high temperature area (hot spot) in the catalyst layer has become a big problem. Since the generation of the hot spot results in a decrease in the catalyst life or a decrease in the yield due to an excessive oxidation reaction, and in a worst case, the occurrence of a runaway reaction, some technologies for suppressing the hot spot have been proposed. For example, Patent Document 1 discloses a technology of lowering hot spot temperature by using a catalyst in which activity is controlled by changing the supported amount and by using a catalyst in which activity is controlled by changing the baking temperature of the catalyst. Patent Document 2 discloses a technology of using a catalyst in which activity is controlled by changing the ratio of apparent density of the catalyst. Patent Document 3 discloses a technology of using a catalyst in which activity is controlled by changing the content of an inactive component of a catalyst molded body and also changing the occupying volume of the catalyst molded body, the kind and/or amount of an alkali metal, and the baking temperature of the catalyst. Patent Document 4 discloses a technology of providing reaction zones in which the occupying volume of the catalyst molded body is changed and mixing an inactive material into at least one reaction zone. Patent Document 5 discloses a technology of using a catalyst in which activity is controlled by changing the baking temperature of the catalyst. Patent Document 6 discloses a technology of using a catalyst in which activity is controlled by changing the occupying volume and baking temperature of the catalyst, and/or the kind and amount of an alkali metal.